FLOW CYTOMETRIC ANALYSIS OF NUCLEAR MATRIX PROTEINS - METHOD AND POTENTIAL APPLICATIONS

The nuclear matrix (NM) is an important structural component of the nu cleus that participates in the regulation of several diverse metabolic processes. Immunometric assays have shown that alterations in NM-asso ciated functions and morphological characteristics may occur as a resu lt of changes in NM composition. Recent evidence suggests that detecti on of quantitative or qualitative changes in nuclear matrix protein (N MP) composition may be useful in the diagnosis of cancer and as a reli able indicator of cell death. We have developed an in situ flow cytome tric technique for the simultaneous detection of specific NMPs and DNA content in fixed, permeabilized cells. Illustrative results from two different applications of these methods involving two different cell l ines (human melanoma and promyelocytic leukemia) are presented, includ ing: 1)measurements of NM breakdown in necrotic and apoptotic cells af ter treatment with the cytotoxic agents camptothecin, etoposide, or hy perthermia; and 2) detection of changes in NMP content immediately aft er heat shock. We demonstrate that the technique is useful for the ide ntification of cell-cycle specificity of NM breakdown and allows corre lations to be made between the kinetics of DNA fragmentation and NMP s olubilization. Furthermore, our studies indicate that flow cytometric detection of changes in NM composition may be useful for identifying d ifferent modes and temporal patterns of cell death. We discuss other p otential applications of the technique and advantages over standard bi ochemical assays. (C) 1996 Wiley-Liss, Inc.